“Why we should care:
“Even if the science of human origins is still a work in progress, the accumulating information about how we got here and indeed what constitutes a member of the human race offers some useful perspectives on matters of scientific and ethical importance.”
By JOHN RENNIE | SMART PLANET
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Replica of the analyzed bone fragment from the Denisovan girl, positioned on a living hand. (Credit: Max Planck Inst. for Evol. Anthro.)
Paleoanthropologists used to pray that they would unearth big troves of intact Neandertal skeletons and well-preserved artifacts that they could comb for clues to the origins of the human race. But these days, they can often get as much or more information straight from the DNA in bone fragments.
Case in point: the newly published genome study in Science from Matthias Meyer and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology and their international team of colleagues. Using a novel DNA sequencing technique that works particularly well with degraded specimens, they examined the genome of a seven-year-old girl who died more than 74,000 years ago, using a surviving sliver from one of her finger bones. That girl’s bone fragment was one of the few pieces of evidence that in 2010 revealed the existence of the ancient Denisovan people — contemporaries of the Neandertals who overlapped with them in eastern Asia.
Matthias Meyer at work in the laboratory. (Credit: Max Planck Inst. for Evol. Anthro.)
Yet from that extraordinarily humble source, the Max Planck scientists have drawn a wealth of insights. They learned, for instance, that the Denisovans were probably dark-skinned, unlike the pale Neandertals. Because the girl had two X chromosomes, one from each parent, the scientists were able to infer that the Denisovan population had relatively little genetic diversity. Living natives of Papua New Guinea, Australia, and some southeast Asian islands derived about 6 percent of their genes from the Denisovans, yet the Denisovans seem to have contributed nothing of lasting value to the DNA of people in other parts of the world. Comparison with the Denisovan DNA also allowed the researchers to recognize that Europeans carry somewhat fewer genes from Neandertals than do East Asians and Native Americans.
Such discoveries are endlessly fascinating to some of us. But I can also understand that many people might reasonably question why any of these details matter. After all, Neandertals and our other ancient ancestors have been extinct for 30,000 years or longer. Why should we care so much about their DNA? Is there any practical value to be had from these studies?
I’ll argue that there is, and that it might be especially useful in helping us to develop more enlightened attitudes about racial differences and autism. To explain why, it may be useful to start by reviewing some of the major current ideas about how humans evolved in the first place.
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